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ICSE Class X Mid-term 2021 : Chemistry

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ST FRANCIS DE SALES PUBLIC SCHOOL Hebbagodi, Electronics City P.O. Bangalore 560100 Std: X MIDTERM EXAMINATION - 2020_Total : 80 Marks CHEMISTRY PAPER - 2 (Two hours) Answers to this paper must be written on the paper provided separately. You will not be allowed to write during first 15 minutes. This time is to be spent in reading the question paper. The time given at the head of this paper is the time allowed for writing the answers. Section I is compulsory. Attempt ANY FOUR questions from Section II. The intended marks for questions or parts of questions are given in brackets []. Section I [40 Marks] Question 1 (a) Choose the most appropriate answer for each of the following (i)An electrolyte which completely dissociates into ions (a) carbonic acid (b) alcohol (c) distilled water (d) sodium hydroxide (ii) The main ore used for the extraction of Aluminium is (a) calamine (b) cryolite (c) haematite (d) bauxite (iii) If the molecular formulae of an organic compound is C12H22. It is (a) alkene (b) alkyne (c) alkane (d) not a hydrocarbon (iv)To increase the pH value of a neutral solution, we should add (a) an acid (b) an acid salt (c) an alkali (d) a salt [5] (v) The molecule containing triple covalent bond is (a) nitrogen (b) ammonia (c) methane (d) water (b) Select from the list the gas that matches the description given in [5] each case. ( ethene, nitrogen, ethane, ammonia, hydrogen chloride, hydrogen sulphide, sulphur dioxide) (i) This gas has a characteristic rotten egg smell (ii) This gas is formed when sulphur is reacted with concentrated sulphuric acid (iii) This gas is used as a reducing agent to convert lead oxide to lead (iv) This gas gives a dense white fumes with ammonia gas (v) This gas is formed when ammonia reacts with heated copper oxide (c) Fill in the blanks (i) Basicity of acetic acid is --------------(ii)Ammonia reacts with excess chlorine to form -------gas (iii) The drying agent used to dry ammonia is ---------------(iv)The chemical formulae of cryolite is---------(v)The acid which produces sugar charcoal from sugar is ------(d) Write the balanced chemical equation for each of the following (i) Laboratory preparation of nitric acid (ii) Action of hot and concentrated nitric acid on copper (iii) Action of dilute sulphuric acid on zinc sulphide (iv) Action of concentrated sulphuric acid on carbon (v) A small piece of zinc is added to dilute hydrochloric acid (e) State one relevant observation for each of the following reactions (i) Action of ammonium hydroxide to ferrous sulphate solution (ii) Alkaline phenolphthalein is added to hydrochloric acid. iii) Action of concentrated sulphuric acid on hydrated copper sulphate. (iv) At the anode ,when molten lead bromide is electrolyzed using graphite electrodes. (v) Silver nitrate solution is added to dilute hydrochloric acid (f) Draw the structural formula of the following compounds (i) 2-methyl prop-1-ene (ii) 2-ethyl-3-methyl pentan -1-al (iii)1,1,2,2-tetrachloeo ethane [5] [5] [5] [5] (g) (h) (iv) 2-bromo butan-1-oic acid (v) propanone [5] Give reason for the following (i)carbon tetrachloride does not conduct electricity (ii)Methane does not undergo addition reaction, but ethene does. iii) Dilute sulphuric acid is stronger than highly concentrated acetic acid (iv)Laboratory prepared nitric acid is light yellow in colour. (v)Polar covalent compounds conduct electricity. [5] Give one word or term for the following (i) formation of ions from molecules (ii)Hydrocarbon containing R-OH functional group. (iii) Substance that releases hydronium ion as the only positive ion when dissolve in water. (iv)A chemical bond formed by sharing of electrons provided entirely by one of the combining atoms. (v) Cation that does not form a precipitate with ammonium hydroxide ,but forms with sodium hydroxide. Section II [40 Marks] (Attempt any FOUR questions) Question 2 [3] (a) Draw the electron dot structure of i) the positive ion formed when ammonia dissolves in water ii) Magnesium chloride iii) Nitrogen molecule (b) [3] The pH value of three solutions A, B, C are given below. Answer the following questions Solution pH A 12 B 2 C 7 (i) which solution will turn red litmus blue? (ii) which solution will liberate CO2 when reacted with sodium carbonate? (iii) Which solution will have no effect on litmus solution? ( c) Answer the following questions based on the extraction of [4] Aluminium by Hall Heraoult process (i) What is the function of cryolite used as an electrolyte? (ii) Why is powdered coke sprinkled on top of the electrolyte? (iii)Write the cathode reaction of this process (iv) Anode has to be replaced in this process. why? Question 3 (a) Answer the following questions [3] (i) How will you distinguish between ammonium hydroxide and sodium hydroxide using copper sulphate solution? (ii) How will you distinguish between dilute hydrochloric acid and dilute sulphuric acid using lead nitrate solution? (iii) How do you distinguish between Carbon dioxide gas and Sulphur dioxide gas? (chemical test) (b) (c) Write the balanced chemical equation for each of the following [4] (i) Manufacture of ammonia (ii) Complete combustion of ethane (iii) Reaction of aluminium with potassium hydroxide solution (iv) Reaction of bauxite with sodium hydroxide [3] You are given an impure block of copper to purify i) Name the anode you would use (ii) Electrolyte you would choose (iii)Write the reaction taking place at the anode. Question 4 [4] (a) The following questions are pertaining to the laboratory preparation of Hydrogen Chloride gas (i) Write the equation for it s preparation mentioning the condition required (ii) Name the drying agent used and justify your choice . (iii) Give one test to identify this gas [3] ( b) Give reasons for each of the following i) Direct absorption of Hydrogen Chloride gas in water is not preferred. (ii) .Solid lead bromide does not conduct electricity . (iii) Sulphuric acid forms two types of salts . [3] (c) The following questions are relevant to the electrolysis of molten lead bromide (i) Write the dissociation of Lead bromide (ii) Write the reaction at the anode and cathode Question 5 (a) Nitric Acid is manufactured by Ostwald s process. Write all the [3] equations involved in this process [2] (b) Write all the steps involved in the substitution reaction of methane with chlorine (c) Give one equation to show the following property of Sulphuric [2] acid (i) As a Non -volatile Acid (ii) Acidic Nature [3] (d) An element X has 2 valence electrons and Y has 6 valence elctrons. (i) show how X and Y form its ions (ii) write the chemical formula formed between X and Y. (iii) Draw the dot structure of formation of the above compound Question 6 (a) (i) Write the balanced chemical equation to prepare ammonia in [1] the laboratory (ii) State why concentrated sulphuric acid is not used for drying [1] ammonia gas. [1] (iii) Why is Ammonia gas not collected over water? [1] (b) (i) What do you understand by catenation? (ii) Draw the electron dot diagram of formation of hydronium [2] ion. [4] (c) (i) Distinguish between ionic compounds and covalent compounds. Question 7 [4] (a) Select the correct answer from the list given in brackets (i) An Aqueous electrolyte consists of the ions mentioned in the list , the ion which could be discharged most readily during electrolysis (Fe2+ , Cu 2+ , Pb2+, H+) (ii) The metallic electrode which doesn t take part in an electrolytic reactions ( Cu, Ag, Pt, Ni) (iii) The ion which is discharged at the anode during the electrolysis of Copper Sulphate Solution using Copper electrodes ( Cu 2+, OH-, SO42-, H+) 4) During silver plating of an article using Potassium argento cyanide as an electrolyte, the anode material should be ( Ag, Cu , Pt, Fe) [2] (b) Differentiate between normal salt and acid salt [3] (c) What are Isomers ? Draw the isomers of Butane [1] (d) Name an Alkene with 5 carbon atoms

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